1. Field of the Invention
The present invention relates to a bell mouth for a scroll case, and more particularly, to a bell mouth for a scroll case having an asymmetric geometry in which the volume of the bell mouth partially increases in the vicinity of a cut off part of the scroll case.
2. Description of the Related Art
In centrifugal blowers that include a scroll case and are widely used as air movement system, gradual expansion of a flow path structure of a scroll case causes energy conversion between pressure energy and kinetic one.
A flow is induced due to a low pressure generated by rotation of a centrifugal blower. However, in a case of some flow regions, reverse flows in axial direction of a centrifugal blower may occur due to nonuniform pressure distribution in circumstance direction. In order to suppress such a reverse flow, extra volume for flows is provided by a bell mouth.
Meanwhile, in a region having an extremely small cross-section area along a flow path of a scroll case, an increase in kinetic energy corresponding to an increase in a flow rate reduces in static pressure in order for satisfaction of energy conservation.
However, it is a well-known fact that if an increase in a flow rate exceeds a predetermined limit, a reverse flow due to an excessive flow rate at a cross-section of a scroll case is observed.
In this case, artificial generation of a low-pressure part by the bell mouth prevents a loss of a flow rate. However, a general bell mouth cannot accomplish this unique object over the entire region nor prevent generation of a reverse flow since it keeps both uniform cross-sectional shape and volume along the circumference.
Since noise and air volume generated in a centrifugal blower vary quite sensitively according to design of a scroll case including bell mouth, researches concerning design of a high-efficiency scroll case or bell mouth are being required in order to reduce noise and increase air volume.